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125KHz rfid circuit design

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Junior Member level 3
Aug 1, 2007
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rfid circuit design

I would like to build my own rfid reader at 125KHz.

The design must serve the functionalities:
1. Very fast oscillator start time
2. Supply voltage low 4,5 to 4V
3. Low antenna current because of the short comunication distanse
4. Shut down function (very low current consumption maximum 5 microAmps)

I have used the EM4095 and HTRC110 in other projects, but for this one they have very slow start time 10 - 35 miliseconds and current consumption is too high, because it is a non rechargable battery system.

Is there any schematic diagram for a good and low cost idea?

Thanks in advance.

rfid circuit

I have seen RFID readers/writers with 1 transistor as oscillator and 1 LM324 working as detector, very fast and nice design. Anyone has a schematic?

Thank You in advance

125khz rfid circuit

hello 1icarus1
iam working on rfid and use htrc110 but when i put the htrc110 in read mode from tag recived data is different in any reading.
can you help me ?
thank you

rfid reader circuit design

Hi there,

I had the same problem in the past, using the HTRC110. Actualy, the data is not different from reading to reading but maybe the data sometimes is polarity inverted and sometimes not. That's why you cannot find the 9 logic "1" (if we are talking about the EM4100 tag).

The solution of this problem is to be carefull when you do the AST method and the settling time.

Also be carefull when you READ_PHASE (command). Remember that this command must be stoped as soon as possible when you read the incoming data. Dont' send 8 bits like the other commands.

I hope I helped,

Good Luck

rfid circuit design and schematic

hi licarus1
thank you for reply my post
i saw by osciloscope DOUT pin of htrc110 when it was in read mode and no tag in filed of antena in this mode i saw pulses.
i think that this pulse is noise . what i do until this noise deleted?
plese help me
thank you

rfid chip circuit design

hye..i would to build a rfid door lock..but i dont get any idea how and where to start..anyone may help me?in this project i'm using a motor, microcontroller 16F877A and parallel RFID..plz help me..


When you say RFID door lock what do you mean?
1. Battery supply system
2. External supply system (5, 12, 24 Vdc)
3. Mains supply system


htrc110 tag read only dout

i means everything..i'm planning to use battery supply system that connected to RFID circuit system and microcontroller system..can u help me?

lm324 rfid schematic

Could you be more analytical???

This is the only way to understand what you are trying to do.


rfid reader design circuit

this my final year project..i'm from this project i need to use RFID to control door lock and unlock..there are 4 parts/circuits..1st circuit is power supply 5V..2nd circuit is parallel data converter to from RFID is parallel right?the data has to convert to serial so that microntroller can read the data..based on the data, microcontroller will control the rotation of motor to control lock or unlock the door..n i only finished the 1st part..can u help me?

build a 125 khz oscillator


This is clear.
You could do this thing using read only tags (EM4100) or read/write tags (AT5567). In order to comunicate with the tags you could use an ic like
EM4095, 4,2 - 5,5V.
or HTRC110 (SPI controlled), 4,5 - 5,5V.

First of all you have to decide of what type of tags are you going to use. You could do this job with both read only or read/write tags.

Using read only tags you have to learn the cards 64bit id to the door lock using let's say a button. Then whenever the door lock read this id, will open the door.

Using read write/cards you have to build a device for writing information inside the blocks, and also you have to address the door locks. So each door will have it's own address. Using the device that write cards you will write inside the blocks the address of the specific door. When a door reads a tag and the address is the same then the door will open.

I think that this was a very good help in order to begin with your research.

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